Hoof accelerations at hoof-surface impact for stride types and functional limb types relevant to show jumping horses

Increased knowledge of the influence of stride type on hoof impact accelerations for fore and hind limbs could lead to a more complete picture of hoof-ground interactions in equine athletes. Hoof accelerations were quantified for each hoof of five show jumping horses using two orthogonal single axis ± 250 g accelerometers. Accelerations were recorded when cantering horses jumped fences of varying types (upright and oxer) and heights (90-130 cm) on three different surface conditions. Strides were identified as normal canter strides, take-off strides and landing strides. Descriptive hoof impact parameters were maximal vertical deceleration (MaZ), range of maximum fore-aft acceleration and deceleration (RaX), quotient of acceleration vectors (arctangent for RaX/MaZ) and hoof breaking duration (time from MaZ to first level of <0.042 g absolute fore-aft acceleration). The highest hoof impact accelerations occurred during the take-off stride (mean MaZ over limbs 52.6-91.6 g vs. all-stride mean 39.8 g; mean RaX 63.9-80.5 g vs. all-stride mean 50.7 g). At the jump landing, the forelimbs also experienced high MaZ (46.8 and 49.0 g) of the same order of magnitude as the forelimbs at the take-off. Non-lead limbs had higher MaZ in the normal canter stride, comparing within forelimb and hind limb pairs, and the reverse relationship occurred for RaX and for the quotient of acceleration vectors. The systematic variation introduced by limb and stride type suggests that these gait parameters are important to understand in a sport-specific context for horse surfaces, especially in the development of standardised testing equipment that simulates horse-surface interactions.